// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_WM_PUBLIC_DRAG_DROP_DELEGATE_H_
#define UI_WM_PUBLIC_DRAG_DROP_DELEGATE_H_

#include "ui/aura/aura_export.h"

namespace ui {
class DropTargetEvent;
}

namespace aura {
class Window;
namespace client {

    // Delegate interface for drag and drop actions on aura::Window.
    class AURA_EXPORT DragDropDelegate {
    public:
        // OnDragEntered is invoked when the mouse enters this window during a drag &
        // drop session. This is immediately followed by an invocation of
        // OnDragUpdated, and eventually one of OnDragExited or OnPerformDrop.
        virtual void OnDragEntered(const ui::DropTargetEvent& event) = 0;

        // Invoked during a drag and drop session while the mouse is over the window.
        // This should return a bitmask of the DragDropTypes::DragOperation supported
        // based on the location of the event. Return 0 to indicate the drop should
        // not be accepted.
        virtual int OnDragUpdated(const ui::DropTargetEvent& event) = 0;

        // Invoked during a drag and drop session when the mouse exits the window, or
        // when the drag session was canceled and the mouse was over the window.
        virtual void OnDragExited() = 0;

        // Invoked during a drag and drop session when OnDragUpdated returns a valid
        // operation and the user release the mouse.
        virtual int OnPerformDrop(const ui::DropTargetEvent& event) = 0;

    protected:
        virtual ~DragDropDelegate() { }
    };

    AURA_EXPORT void SetDragDropDelegate(Window* window,
        DragDropDelegate* delegate);
    AURA_EXPORT DragDropDelegate* GetDragDropDelegate(Window* window);

} // namespace client
} // namespace aura

#endif // UI_WM_PUBLIC_DRAG_DROP_DELEGATE_H_
